Fuel nozzles and combustion equipment

Abstract

The present invention relates to a fuel nozzle, comprising: a channel, at least two flow guides are arranged in the channel, the flow guides are spiral flow guides, and a spiral channel is defined between the flow guides, wherein: the channel has an inner wall surface, the flow guides are integral with the inner wall surface; and in the fuel outlet end surface of the channel, the sum of the areas of the flow guides is 10-50% of the circular area defined by the inner wall surface. The present invention also relates to a combustion device having the above-mentioned fuel nozzle.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of combustion, and in particular to a fuel nozzle and a combustion device. Background Art

[0002] The combustion efficiency of high-temperature solid fuel and the formation of pollutants during combustion are affected by the fuel and secondary air flow field organization. Due to the high temperature of hot fuel, which can generally reach above 700°C, the conventional pulverized coal burner cannot effectively organize the hot fuel flow field safely and stably due to the high temperature and wear of the hot fuel.

[0003] The known solution is to set the hot fuel outlet as a simple channel, through which the hot fuel passes to form a hot fuel bundle, and at the same time arrange supplementary combustion air outside the hot fuel bundle. In this way, the hot fuel bundle has strong rigidity, the furnace filling degree is poor, and the residence time of the fuel in the furnace is limited, which is prone to problems such as short combustion time and low combustion efficiency; in addition, the hot fuel bundle and the supplementary combustion air are only in contact through the external flame front, and the contact area between the fuel and oxygen is limited, making it difficult to organize the combustion, and it is easy to generate high temperature in some parts, and other parts cannot be burned out, which also affects the combustion efficiency. Summary of the invention

[0004] The present invention is proposed to alleviate or solve at least one aspect or at least one point of the above problems.

[0005] According to one aspect of an embodiment of the present invention, a fuel nozzle is provided, comprising:

[0006] A channel is provided with at least two flow guides in the channel, wherein the flow guides are spiral flow guides, and a spiral channel is defined between the flow guides, wherein:

[0007] The channel has an inner wall surface, and the flow guide is integral with the inner wall surface; and

[0008] In the fuel outlet end surface of the channel, the sum of the areas of the flow guides is 10-50% of the circular area defined by the inner wall surface.

[0009] According to another aspect of an embodiment of the present invention, a combustion system is provided, comprising:

[0010] Burning space;

[0011] At least one nozzle is suitable for providing fuel into the combustion space, and the at least one nozzle includes the above-mentioned fuel nozzle. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a schematic cross-sectional view of a portion of a fuel injection port according to an exemplary embodiment of the present invention;

[0013] Figure 2 along Figure 1 A schematic longitudinal section diagram of the fuel nozzle in the AA direction;

[0014] Figure 3 for Figure 2 A schematic cross-sectional view of the fuel nozzle in the C direction;

[0015] Figure 4 A schematic longitudinal section view of a portion of a fuel nozzle according to an exemplary embodiment of the present invention;

[0016] Figure 5 for Figure 4 A schematic cross-sectional view of a fuel nozzle shown in FIG. 1 , the cross-section passing through the secondary air duct;

[0017] Figure 6 is a schematic cross-sectional view of a portion of a fuel nozzle according to an exemplary embodiment of the present invention, wherein a secondary air duct is provided between flow guide members;

[0018] Figure 7 It is a schematic cross-sectional view of a portion of a fuel nozzle according to an exemplary embodiment of the present invention, wherein a secondary air duct penetrates through a flow guide. DETAILED DESCRIPTION

[0019] The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the overall inventive concept of the present invention, and should not be construed as a limitation of the present invention. In the present invention, the same reference numerals represent the same or similar components.

[0020] Figure 1 is a schematic cross-sectional view of a fuel nozzle according to an exemplary embodiment of the present invention, Figure 2 along Figure 1 A schematic cross-sectional view of the fuel nozzle in the AA direction, Figure 3 for Figure 2 Schematic diagram of the cross-section of the fuel nozzle in the C direction.

[0021] like Figure 1-Figure 3 As shown, the fuel nozzle includes a fuel passage 10 having a certain wall thickness d and an inner diameter D (see Figure 3 ), a guide member 11 is provided on the inner wall surface of the fuel channel 10, and the guide member 11 is integrally provided with the wall surface of the fuel channel 10.

[0022] The guide member 11 is a spiral structure with a spiral angle a (see Figure 2) is in the range of 5 to 15°. In this way, when the fuel passes through the nozzle, it is arranged into a swirl with an inclination of 5 to 15°. After the fuel leaves the nozzle, it will further diffuse in the combustion space, the rigidity of the fuel will be weakened, the diffusion capacity will be significantly improved, the residence time in the combustion space and the contact surface with the combustion aid will be expanded, thereby improving the combustion efficiency. Further optionally, the helical angle of the guide is between 8 and 13°. This combustion organization is completely different from the traditional organization of cold coal powder directly entering the furnace for combustion, and is suitable for improving the combustion efficiency of high-temperature gas-solid mixed fuel.

[0023] In the present invention, the wall surface of the fuel channel 10 is cast with a fire-resistant and wear-resistant castable material, and can be integrally cast with the flow guide 11 .

[0024] In the present invention, a plurality of flow guides 11 are provided along the circumferential direction of the fuel channel, for example, 2 to 12, and further, 4 to 10.

[0025] In an exemplary embodiment of the present invention, in the fuel outlet end face of the channel 10, the sum of the areas of the guide members 11 is 10-60% of the circular area (with a diameter D) defined by the inner wall of the channel, and further optionally, 15-50%.

[0026] In the embodiment of the present invention, the cross-sectional shape of the guide member 11 at different cross sections perpendicular to the axial direction of the fuel nozzle is rectangular or triangular.

[0027] In another embodiment of the present invention, the cross-sectional areas of the guide member 11 in different cross sections perpendicular to the axial direction of the fuel nozzle remain constant.

[0028] In another embodiment of the present invention, the cross-sectional area of ​​the guide member 11 at different cross sections perpendicular to the axial direction of the fuel nozzle gradually decreases in the direction from the outlet end face of the fuel nozzle to the fuel inlet until it finally coincides with the inner wall surface of the fuel channel 11, so as to achieve smooth entry of the fuel into the guide device, reduce the resistance of the guide member to the fuel flow, maintain its momentum and avoid loss.

[0029] In the present invention, the length of the guide member 11 in the axial direction of the fuel channel 10 from the outlet end face of the channel is in the range of 1D-2.5D, so that the fuel flow is arranged into a swirl with relatively less momentum loss, which has a good effect on fuel rectification.

[0030] In the present invention, the fuel nozzle may further include a secondary air inlet, which opens into the channel 11 , that is, the secondary air directly flows into the channel 11 .

[0031] Figure 4 A schematic longitudinal section view of a portion of a fuel nozzle according to an exemplary embodiment of the present invention; Figure 5 for Figure 4 Schematic diagram of a cross-section of a fuel nozzle shown in , the section passing through the secondary air duct. Figure 4 and Figure 5 The reference numeral 12 in the figure corresponds to the secondary air duct. Figure 5 As shown, the secondary air duct 12 is arranged at the center of the fuel nozzle, and the opening of the secondary air duct 12 is located in the channel 10 and is spaced a distance from the outlet end face of the channel 10 (see Figure 4 ).

[0032] In one embodiment of the present invention, the distance between the secondary air inlet and the outlet end face of the channel 10 in the axial direction of the channel 10 is within the range of 0.5D-1.0D. The position of the secondary air inlet is very important for achieving deep graded combustion of the fuel, maintaining the safety of the fuel nozzle, and avoiding slagging of hot fuel. Different from the general cold fuel combustion organization, in the hot fuel combustion organization used in the present invention, if the secondary air is introduced into the fuel channel too early, the fuel will burn prematurely, the temperature will further increase, the volume of the mixed fuel will increase too much, etc.; if the secondary air is introduced too late, it is easy to produce poor mixing of the fuel and the secondary air. Therefore, based on simulation and hot tests, it is selected to set the position of the secondary air inlet between 0.5D and 1.0D from the outlet end face of the channel 10.

[0033] By introducing the secondary air into the fuel channel 10, on the one hand, the fuel and the secondary air are directly mixed. Since the temperature of the fuel itself is higher than the ignition point of the fuel, deep staged combustion occurs when the secondary air meets the fuel. In a reducing atmosphere, the deep staged combustion of the fuel is beneficial to the conversion of nitrogen in the fuel into N2, thereby reducing the generation of fuel-type NOx in subsequent combustion.

[0034] At the same time, passing the secondary air into the fuel channel 10 can also increase the carrying wind speed in the fuel channel, thereby making the fuel flow faster when leaving the nozzle. After the swirl reduces the flame stiffness, it ensures that the fuel has a higher radial diffusion speed, thereby ensuring the fullness of the fuel in the combustion space.

[0035] After the secondary air enters the channel 10, it partially burns the fuel, so that the fuel is continuously heated and burns in depth and in stages, which is more conducive to the combustion organization of the fuel after leaving the fuel channel and entering the furnace.

[0036] The way in which the secondary air enters the channel 10 is not limited to Figure 4 and Figure 5 The method shown in .

[0037] In one embodiment of the present invention, the secondary air channel penetrates the wall of the fuel channel 10. In one embodiment, the secondary air channel penetrates the wall of the fuel channel 10 horizontally from the outside, and does not intersect with the guide member 11, such as Figure 6 As shown in FIG. 12 , the secondary air channel inlet is arranged on the wall surface between two adjacent guide members, the number of which is not greater than the number of guide members, and is evenly distributed in the circumferential direction, as shown in FIG. Figure 6 In the embodiment, there are 8 guide members, and the secondary air channel inlet can be set to 4; in another embodiment, the secondary air channel and the guide member are interpenetrating, such as Figure 7 As shown in FIG. 12 , the secondary air channel passes through the side wall of the channel 10 and the air guide 11 , and the secondary air inlet opens at the end surface of the air guide 11 facing the central axis of the channel 10 .

[0038] exist Figure 6 and Figure 7 The cross section obtained along line AA is Figure 2 The cross sections shown are similar and will not be described again here.

[0039] In another embodiment of the present invention, although not shown, the secondary air channel is arranged in the wall surface of the fuel channel 10, and optionally, the axis of the secondary air channel is parallel to the axis of the fuel channel, and the end of the secondary air channel away from the air flow source intersects with the inner wall surface of the fuel channel so that the secondary air outlet opens in the channel 10, that is, the secondary air passes through the secondary air channel and enters the fuel channel 10 from the secondary air outlet at the wall surface of the fuel channel 10. In addition, arranging the secondary air channel in the wall surface of the fuel channel 10 can also cool the wall surface of the fuel channel 10, and is conducive to reducing the weight of the fuel channel 10 and reducing the cost of processing materials.

[0040] In another embodiment of the present invention, the secondary air channel is a tubular channel coaxially nested inside the fuel channel 10, such as Figure 4 As shown in 12. The gas coming out of the secondary air outlet is a swirl (which can be achieved by setting a swirl functional structure in the secondary air channel 12. In the embodiment of the present invention, the swirl functional structure can be achieved by a special swirl guide vane, or by making the secondary air outlet channel inclined). The direction of the swirl formed is consistent with the rotation direction of the fuel channel guide. Here, the swirl direction formed when the secondary air enters the channel is consistent with the rotation direction of the guide, which means that the rotation directions of the two are consistent, including not only that the swirl angles of the two are roughly consistent, but also that the rotation directions are consistent, such as clockwise or counterclockwise. In a further embodiment of the present invention, the secondary air channel can be arranged in a spiral channel defined by the guide 11.

[0041] In an exemplary embodiment of the present invention, the fuel nozzle is a high-temperature fuel nozzle, that is, the temperature of the fuel flow entering the fuel nozzle is not less than 700°C.

[0042] The above-mentioned fuel nozzle proposed in the present invention can be arranged in a boiler or a kiln. Accordingly, the present invention proposes a combustion device, which comprises the fuel nozzle according to the present invention, and the fuel enters into the combustion space of the combustion device through the fuel nozzle.

[0043] Based on the above, the present invention proposes the following technical solutions:

[0044] 1. A fuel nozzle, comprising:

[0045] A channel is provided with at least two flow guides in the channel, wherein the flow guides are spiral flow guides, and a spiral channel is defined between the flow guides, wherein:

[0046] The channel has an inner wall surface, and the flow guide is integral with the inner wall surface; and

[0047] In the fuel outlet end surface of the channel, the sum of the areas of the flow guides is 10-60% of the circular area defined by the inner wall surface.

[0048] 2. The fuel nozzle according to item 1, wherein:

[0049] The helix angle of the flow guide is in the range of 5-15°.

[0050] 3. The fuel nozzle according to 2, wherein:

[0051] The helix angle of the flow guide is in the range of 8-13°.

[0052] 4. The fuel nozzle according to item 1, wherein:

[0053] The number of the guide members is in the range of 2-12.

[0054] 5. The fuel nozzle according to claim 4, wherein:

[0055] The number of the guide members is in the range of 4-10.

[0056] 6. The fuel nozzle according to item 1, wherein:

[0057] The cross-sectional area of ​​the guide member at different cross sections perpendicular to the axial direction of the fuel nozzle remains constant; or

[0058] The cross-sectional areas of the flow guide member at different cross sections perpendicular to the axial direction of the fuel nozzle gradually decrease in the direction from the outlet end surface of the fuel nozzle to the fuel inlet.

[0059] 7. The fuel nozzle according to item 1, wherein:

[0060] The cross-sectional shape of the flow guide member at different cross-sections perpendicular to the axial direction of the fuel nozzle is rectangular or triangular.

[0061] 8. The fuel nozzle according to item 1, wherein:

[0062] In the fuel outlet end surface of the channel, the sum of the areas of the flow guides is 15-50% of the area of ​​the circle defined by the inner wall surface.

[0063] 9. A fuel nozzle according to any one of 1-8, wherein:

[0064] The diameter of the circle defined by the inner wall surface is D;

[0065] The length of the flow guide member from the outlet end surface of the channel in the axial direction of the channel is in the range of 1D-2.5D.

[0066] 10. A fuel nozzle according to any one of 1-8, wherein:

[0067] The fuel nozzle further includes a secondary air outlet, and the secondary air outlet opens into the passage.

[0068] 11. The fuel nozzle according to 10, wherein:

[0069] The fuel nozzle includes a secondary air flow path through the side wall of the channel.

[0070] 12. The fuel nozzle according to 11, wherein:

[0071] The secondary air flow path passes through the channel side wall and is located between adjacent air guides in the circumferential direction; or

[0072] The secondary air flow path passes through the channel side wall and the air guide, and the secondary air outlet opens at the end surface of the air guide facing the central axis of the channel.

[0073] 13. The fuel nozzle according to 12, wherein:

[0074] The number of the secondary air outlets is less than the number of the guide members, and the secondary air outlets are arranged at equal intervals in the circumferential direction;

[0075] 14. The fuel nozzle according to 10, wherein:

[0076] The diameter of the circle defined by the inner wall surface is D;

[0077] The distance between the secondary air outlet and the outlet end surface of the channel in the axial direction of the channel is in the range of 0.5D-1.0D.

[0078] 15. The fuel nozzle according to 10, wherein:

[0079] The fuel injection port includes a secondary air flow path, at least a portion of which is disposed in a side wall of the passage.

[0080] 16. The fuel nozzle according to 10, wherein:

[0081] The fuel nozzle includes a secondary air flow path, and the secondary air flow path is coaxially nested in the channel.

[0082] 17. The fuel nozzle according to 16, wherein:

[0083] At least a portion of the secondary air flow path is located in the spiral channel.

[0084] 18. The fuel nozzle according to 16, wherein:

[0085] The fuel nozzle includes a secondary air duct arranged in the channel, the axis of the secondary air duct is arranged to coincide with the axis of the channel, and the secondary air outlet is arranged at the end position of the secondary air duct.

[0086] 19. The fuel nozzle according to 18, wherein:

[0087] The structure or position of the secondary air outlet is arranged so that the rotation direction of the secondary air entering the channel is consistent with the rotation direction defined by the guide member.

[0088] 20. A fuel nozzle according to any one of 1-19, wherein:

[0089] The fuel nozzle is a fuel nozzle suitable for a fuel flow having a temperature not lower than 700° C. to pass through.

[0090] 21. A combustion device comprising:

[0091] Burning space;

[0092] At least one nozzle is suitable for providing fuel into the combustion space, and the at least one nozzle includes a fuel nozzle according to any one of 1-20.

[0093] In the present invention, each numerical range, except for explicitly indicating that it does not include an endpoint value, can be an endpoint value or a median value of each numerical range, all of which are within the protection scope of the present invention.

[0094] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made to the embodiments and combinations of elements may be made without departing from the principles and spirit of the invention, the scope of the invention being defined by the appended claims and their equivalents.

Claims

1. A fuel nozzle suitable for high-temperature solid fuel with a fuel temperature not less than 700°C, comprising: A channel is provided with at least two flow guides in the channel, wherein the flow guides are spiral flow guides, and a spiral channel is defined between the flow guides, wherein: The channel has an inner wall surface, and the flow guide is integral with the inner wall surface; and In the fuel outlet end face of the channel, the sum of the areas of the flow guides is 10-60% of the circular area defined by the inner wall surface; The fuel nozzle further includes a secondary air outlet, and the secondary air outlet opens into the passage.

2. The fuel nozzle according to claim 1, wherein: The helix angle of the flow guide is in the range of 5-15°.

3. The fuel nozzle according to claim 2, wherein: The helix angle of the flow guide is in the range of 8-13°.

4. The fuel nozzle of claim 1, wherein: The number of the guide members is in the range of 2-12.

5. The fuel nozzle of claim 4, wherein: The number of the guide members is in the range of 4-10.

6. The fuel nozzle of claim 1, wherein: The cross-sectional area of ​​the guide member at different cross sections perpendicular to the axial direction of the fuel nozzle remains constant; or The cross-sectional areas of the flow guide member at different cross sections perpendicular to the axial direction of the fuel nozzle gradually decrease in the direction from the outlet end surface of the fuel nozzle to the fuel inlet.

7. The fuel nozzle of claim 1, wherein: The cross-sectional shape of the flow guide member at different cross-sections perpendicular to the axial direction of the fuel nozzle is rectangular or triangular.

8. The fuel nozzle of claim 1, wherein: In the fuel outlet end surface of the channel, the sum of the areas of the flow guides is 15-50% of the area of ​​the circle defined by the inner wall surface.

9. The fuel nozzle according to any one of claims 1 to 8, wherein: The diameter of the circle defined by the inner wall surface is D; The length of the flow guide member from the outlet end surface of the channel in the axial direction of the channel is in the range of 1D-2.5D.

10. The fuel nozzle of claim 9, wherein: The fuel nozzle includes a secondary air flow path through the side wall of the channel.

11. The fuel nozzle of claim 10, wherein: The secondary air flow path passes through the channel side wall and is located between adjacent air guides in the circumferential direction; or The secondary air flow path passes through the channel side wall and the air guide, and the secondary air outlet opens at the end surface of the air guide facing the central axis of the channel.

12. The fuel nozzle of claim 11, wherein: The number of the secondary air outlets is less than the number of the air guide members, and the secondary air outlets are arranged at equal intervals in the circumferential direction.

13. The fuel nozzle of claim 9, wherein: The diameter of the circle defined by the inner wall surface is D; The distance between the secondary air outlet and the outlet end surface of the channel in the axial direction of the channel is in the range of 0.5D-1.0D.

14. The fuel nozzle of claim 9, wherein: The fuel injection port includes a secondary air flow path, at least a portion of which is disposed in a side wall of the passage.

15. The fuel nozzle of claim 9, wherein: The fuel nozzle includes a secondary air flow path, and the secondary air flow path is coaxially nested in the channel.

16. The fuel nozzle of claim 15, wherein: At least a portion of the secondary air flow path is located in the spiral channel.

17. The fuel nozzle of claim 15, wherein: The fuel nozzle includes a secondary air duct arranged in the channel, the axis of the secondary air duct is arranged to coincide with the axis of the channel, and the secondary air outlet is arranged at the end position of the secondary air duct.

18. The fuel nozzle of claim 17, wherein: The structure or position of the secondary air outlet is arranged so that the rotation direction of the secondary air entering the channel is consistent with the rotation direction defined by the guide member.

19. A combustion device comprising: Burning space; At least one nozzle is adapted to provide fuel into the combustion space, and the at least one nozzle comprises a fuel nozzle according to any one of claims 1-18.

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